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author | Maxim Yurchuk <maxim-yurchuk@ydb.tech> | 2024-10-18 20:31:38 +0300 |
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committer | GitHub <noreply@github.com> | 2024-10-18 20:31:38 +0300 |
commit | 2a74bac2d2d3bccb4e10120f1ead805640ec9dd0 (patch) | |
tree | 047e4818ced5aaf73f58517629e5260b5291f9f0 /contrib/libs/cxxsupp/builtins/ppc/floattitf.c | |
parent | 2d9656823e9521d8c29ea4c9a1d0eab78391abfc (diff) | |
parent | 3d834a1923bbf9403cd4a448e7f32b670aa4124f (diff) | |
download | ydb-2a74bac2d2d3bccb4e10120f1ead805640ec9dd0.tar.gz |
Merge pull request #10502 from ydb-platform/mergelibs-241016-1210
Library import 241016-1210
Diffstat (limited to 'contrib/libs/cxxsupp/builtins/ppc/floattitf.c')
-rw-r--r-- | contrib/libs/cxxsupp/builtins/ppc/floattitf.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/contrib/libs/cxxsupp/builtins/ppc/floattitf.c b/contrib/libs/cxxsupp/builtins/ppc/floattitf.c new file mode 100644 index 0000000000..6deac64981 --- /dev/null +++ b/contrib/libs/cxxsupp/builtins/ppc/floattitf.c @@ -0,0 +1,46 @@ +//===-- lib/builtins/ppc/floattitf.c - Convert int128->long double -*-C -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements converting a signed 128 bit integer to a 128bit IBM / +// PowerPC long double (double-double) value. +// +//===----------------------------------------------------------------------===// + +#include <stdint.h> + +// Conversions from signed and unsigned 64-bit int to long double. +long double __floatditf(int64_t); +long double __floatunditf(uint64_t); + +// Convert a signed 128-bit integer to long double. +// This uses the following property: Let hi and lo be 64-bits each, +// and let signed_val_k() and unsigned_val_k() be the value of the +// argument interpreted as a signed or unsigned k-bit integer. Then, +// +// signed_val_128(hi,lo) = signed_val_64(hi) * 2^64 + unsigned_val_64(lo) +// = (long double)hi * 2^64 + (long double)lo, +// +// where (long double)hi and (long double)lo are signed and +// unsigned 64-bit integer to long double conversions, respectively. +long double __floattitf(__int128_t arg) { + // Split the int128 argument into 64-bit high and low int64 parts. + int64_t ArgHiPart = (int64_t)(arg >> 64); + uint64_t ArgLoPart = (uint64_t)arg; + + // Convert each 64-bit part into long double. The high part + // must be a signed conversion and the low part an unsigned conversion + // to ensure the correct result. + long double ConvertedHiPart = __floatditf(ArgHiPart); + long double ConvertedLoPart = __floatunditf(ArgLoPart); + + // The low bit of ArgHiPart corresponds to the 2^64 bit in arg. + // Multiply the high part by 2^64 to undo the right shift by 64-bits + // done in the splitting. Then, add to the low part to obtain the + // final result. + return ((ConvertedHiPart * 0x1.0p64) + ConvertedLoPart); +} |